Особенности теплового состояния человека при использовании защитного комплекта от электрических полей промышленной частоты

Abstract

Abstract. Introduction. When using personal protective equipment (PPE) against power-frequency electric fields (PFEF), there is a problem associated with the deterioration of the humans thermal state during a workshift when working in a hot environment. The shielding and shunting elements of the PPE increase the weight of the PPE and has an additional thermal load on a person working in a hot environment and so have a negative impact on his thermal state. The change in the indicators of the persons’ thermal state can be considered as a criteria for the impact of a complex of factors that determine the body heat exchange with the environment. Also, in addition to the impact of the PFEF and the hot environment, workers are exposed to physical exertion associated with moving around the area and lifting weights, which additionally burdens their functional state. Purpose. To study the thermal state of a person using PPE from the PFEF, when performing physical work at different thermal load levels of the environment. Materials and methods. Four practically healthy men were involved as volunteers. Before and after the experiment, the initial skin temperature indicators were recorded in 11 areas of the body surface as well as the tympanic membrane temperature and the heart rate (HR). During physical activity and rest, subjective heat and humidity sensations were also recorded every 5 minutes on the 11 areas of the body surface and the temperature of the inner surface of the clothing was determined. Before and after the experiment, the body weight of the naked volunteer and the weight of all the items included in the PPE kit were recorded. Results and discussion. During physical work at WBGT 28.0°C, ΔQts reached the permissible level (2.6 kJ/kg) after 10 minutes from the start of the work, and when working in WBGT 23.3°C – after 20 minutes, which indicated the highest rate of overheating of the human body at a higher level of the thermal load. The moisture sensitivity score at WBGT of 28.0°C by the end of the working period was 3.3. Stabilization of the HR was observed at a lower level of the thermal load, but at WBGT 28.0°C there was a HR continuous increase, which indicates a greater tension of the thermoregulation mechanisms. Conclusion. The obtained data allowed us to establish the fact of the negative impact of the use of EP-4(0) kits on the humans’ thermal state. When using the EP-4(0), it is necessary to regulate the time of continuous work in the open air: no more than 2 hours with a subsequent rest for at least 30 minutes in order to compensate heat loss as a result of using such PPE, which hinders heat and moisture exchange.